1. Field of the Invention
The present invention relates to a wire bonding formation for semiconductor industry, and more particularly to a profile design for wire bonding to prevent the wire from necking and fracture in the process of bonding, thereby providing an optimum design for wire bonding profiles in package fabrication technologies for semiconductors.
2. Description of the Related Art
The semiconductor package provides electrical connection and mechanical and environmental protection for the semiconductors. Cost and/or performance considerations of the packaged device usually dictate the assembly and packaging details. Packaging significantly affects, and in many instances dominates, the overall cost, performance, and reliability of the packaged die. Packaging is now receiving more attention by both packaged-device venders and system builders. Recently, developments of the package fabrication technologies in the semiconductor industry are significant, and a trend thereof is thin, fine and small such that qualitative and quantitative analysis in the bonding track of the wire become extremely important as the result of the analysis may provide effective, valuable information to avoid necking and/or fracture for the bonded wire during packaging process. It is therefore an issue of research and development in the semiconductor industry to analyze and simulate how forces acting on the fine wire interconnection during the bonding formation and to construct an optimal profile by means of simulating a simple model for the fine wire interconnection. U.S. Pat. No. 4,932,384 to Yamazaki et al. and U.S. Pat. No. 5,205,463 to Holdgrafer et al. proposed several wire bonding traces/loops to avoid necking and fracture in the wire bonding process. Currently, analysis of the formation process of the bonding wire is usually based on experimental statistics which is time-consuming and unable to use quantitative analysis and is subjected to complexity of conventional finite element method for elastic-plastic large deformation analysis of metal. Therefore, the finite element method for elastic-plastic large deformation analysis of metal is not found in domestic and foreign references for quantitative analysis of wire bonding technologies. Simulation of the wire bonding is either concerned with commercial secret or difficult to be analyzed quantitatively, and it would be of great aid in subsequent development of the wire bonding technologies if the relevant technique is controlled.
The present invention provides a method of linkage with springs to simulate the condition of forces-acting on a section of the bonding wire, and the bonding wire profile can be formed by means of combining several sets of linkage with springs, wherein the coefficients of elasticity of the springs are determined by the bending angle of two linkages which simulates the elastic-plastic deformation of the linkages. The operational model can be simplified and the time can be saved by using the multiple degrees of freedom of the links/springs to analyze the profile of and forces on the fine wire. Necking and fracture during formation process of the bonding wire can be avoided by the present method and design to achieve the optimum design for wire bonding profiles.